The present invention relates to a microelectronic assembly. More specifically, the present invention relates to a microelectronic assembly having slidable electrical contacts between an integrated circuit component and a substrate.
A typical microelectronic assembly includes an integrated circuit component mounted onto a substrate, such as a printed circuit board, by solder joints. The integrated circuit component may be a flip-chip with bond pads arranged on a face that faces the substrate. The face is spaced apart from the substrate by a gap. The substrate includes terminals opposite the bond pads. The bond pads are aligned with the terminals on the substrate. The bond pads and the corresponding terminals are electrically and mechanically connected through solder joints commonly referred to as solder bumps. The gap is commonly filled with an encapsulant to reduce stress upon the solder bumps.
Semiconductor manufacturers historically have increased the density of solder bumps on flip-chips. However, as adjacent solder bumps are placed closer together, adjacent solder joints tend to merge or contact one another during reflow creating electrical short circuits; hence, defective microelectronic assemblies. Electrical short circuits are particulary troublesome in the manufacturing of microelectronic assemblies using fine-pitch flip-chips. In practice, conventional solder bumps frequently do not offer acceptable manufacturing reliability or yields for fine pitch interconnections of 153 microns or less.
Conventional solder bump interconnections form generally rigid joints that may fail when exposed to sufficient thermal or mechanical stress during manufacturing or use of the microelectronic assembly. For example, during operation of a microelectronic assembly, the microelectronic assembly may be subjected to a temperature increase that cause the integrated circuit component to expand at a different rate than the substrate does. That is, the substrate and the integrated circuit component typically have different coefficients of thermal expansion. Thus, even if the same degree of heat is applied to the substrate and the integrated circuit die, the rigid solder joints are subjected to stress which may lead to breakage of solder joints and open circuits.
An integrated circuit die is often difficult to remove from the microelectronic assembly without damaging it. Removal of an integrated circuit component typically involves heating multiple solder bumps, which may thermally damage the integrated circuit component and any surrounding electrical components on the substrate. The integrated circuit component is typically affixed to the substrate by an underfilling encapsulant after soldering to reduce stress on the solder joints. Accordingly, removal of the integrated circuit die requires the arduous separation of the integrated circuit die from the underfilling encapsulant that binds the integrated circuit die to the substrate.
Thus, a need exists for a microelectronic assembly and an interconnection method that provides reliable, stress-tolerant electrical interconnections, while featuring a readily-removable integrated circuit component. In addition, a need exists for a microelectronic assembly and a method for producing reliable and stress-tolerant electrical interconnections, which are well-suited for fine pitch technology with flip-chips having fine pitches of less than or equal to 153 microns.